In recent years, a position detection apparatus of a capacitance type has been vigorously developed as position detection means for a pointer (a finger, a pen type position pointer or the like) used for a touch panel or the like. As the capacitance method, two kinds of methods including a surface capacitive type (Surface Capacitive Type) method and a projected capacitive type (Projected Capacitive Type) method are available, and, in both methods, a variation of a capacitive coupling state between a sensor electrode and a pointer is detected to detect the position of the pointer.
Also, a position detection apparatus has been developed which applies a method called cross-point capacitive coupling method, created by developing the projection type capacitance method. A schematic configuration of a cross-point capacitive coupling type position detection apparatus in the proximity of a sensor section is shown in FIG. 8. An operation principle of the capacitance type position detection apparatus is described using the cross-point capacitive coupling type position detection apparatus as an example.
A sensor section of the position detection apparatus of the cross point capacitive coupling type is configured such that, as shown in FIG. 8, a plurality of upper electrodes Ex and a plurality of lower electrodes Ey are juxtaposed, for example, in an X axis direction (lateral direction) and a Y axis direction (longitudinal direction) on a pointing inputting face such that they extend perpendicularly to each other and are arrayed with a small gap left therebetween. In this instance, a capacitor Co (fixed capacitance) is formed at each of overlapping portions (cross points) between the upper electrodes Ex and the lower electrodes Ey.
Further, at a position of the pointing inputting face, at or near which a pointer 100, such as a position pointer held by a user or a finger or the like of the user, is positioned or contacts the pointing inputting face, a capacitor Cf is formed between the upper and lower electrodes Ex and Ey at the position and the pointer. Still further, the pointer 100 is connected to the ground through a predetermined capacitor Cg via the human body. As a result, the charge transfer amount between the upper electrode Ex and the lower electrode Ey varies at the position of the pointer 100 due to the capacitors Cf and Cg. In the position detection apparatus of the cross point capacitive coupling type, the variation of the charge transfer amount is detected to specify the position pointed to by the pointer 100 on the pointing inputting face.
As a cordless type position pointer used with such a position detection apparatus of the capacitive type as described above, various types of pointers are known as disclosed, for example, in Patent Document 1 (Japanese Patent Laid-Open No. 2000-122799), Patent Document 2 (Japanese Patent Laid-Open No. Hei 10-161796), Patent Document 3 (Japanese Patent Laid-Open No. Hei 7-225646), Patent Document 4 (Japanese Patent Laid-Open No. Hei 10-171579), Patent Document 5 (Japanese Patent Laid-Open No. Hei 7-225645) and so forth.
The position pointers disclosed in Patent Documents 1 to 5 all have a configuration of a pen and include a contacting member, which is made of a conductive material and provided at the tip of a pen. A user of any of these position pointers carries out position pointing by placing the contacting member in contact with a sensor of the position detection apparatus of the capacitive type.
As a result, the contacting member at the end of the pen of the position pointer disclosed in any of Patent Documents 1 to 5 is abraded by contact with the sensor of the position detection apparatus. However, since the contacting member at the end of the pen of the position pointer disposed in any of Patent Documents 1 to 5 is secured to a housing, it is not possible to replace the contacting member by itself, and instead the entire position pointer must be replaced in the case where the contacting member is abraded.
In contrast, in Patent Document 6 (U.S. Published Application No. 2009/0008162 Al) and Patent Document 7 (U.S. Published Application No. 2009/0262637 A1), position pointers are disclosed wherein a contact member is removably mounted. In particular, the position pointer disclosed in either of Patent Document 6 and Patent Document 7 is configured such that a fitting portion for a contacting member is provided on a housing of a position pointer and a contacting member is removably fitted in the fitting portion. Accordingly, with the cited documents 6 and 7, when the contacting member is abraded, only the contacting member may be replaced.